1. Field of the Invention
The present invention relates generally to apparatus for separating individual sheet-like material from a stack and feeding the same to a utilization device. More particularly, the present invention relates to a vacuum type picker mechanism.
2. Prior Art
The use of devices which separate sheet-like articles from a stack and transport the same to utilization apparatuses for further processing are well known in the prior art.
The prior art devices can be broadly divided into two classes. One type of prior art device is adapted for handling relatively stiff sheet-like articles such as veneer sheets, metal sheets or the like. The other type of prior art devices are adapted to handle flexible sheet-like articles such as paper sheets.
U.S. Pat. No. 3,404,789 is an example of the first type of prior art device. The patent describes a prior art device for separating and transporting stiff sheet-like articles such as metal sheets. Stacks of the articles are loaded sequentially onto a support platform. A pick-up device consisting of a pair of vertically reciprocating vacuum pick-ups is descended onto the stack. The topmost metal sheet is picked up and transported by the vacuum pick-ups along a vertical path to a transition zone above the stack. Several magnetic rails are placed in spaced relation at the transition zone. As the vacuum pick-ups retract beyond the bottom surface of the magnetic rails, the metal sheets are magnetically attracted and supported by the rails. A horizontal transport assembly having a plurality of rollers, are interspersed between the magnetic rails. The configuration between the magnetic rails and the rollers are such that the surfaces of the rollers extend slightly beyond the surface of the magnetic rail. The rollers are mounted when the levers are activated on spaced apart shafts and the shafts are connected to mechanical levers. A sheet which is held by the magnetic rail is shifted axially along the rollers.
German Pat. No. 2,502,668 describes an apparatus for lifting and removing veneer sheets from a stack and transporting said sheets to a utilization station. The topmost veneer sheet in the stack is lifted and is held against a movable conveyor belt by a vacuum lifting means. The movable conveyor belt transports the veneer sheet so that the leading edge contacts a rotating brush. The sheet is driven, by the brush, into the utilization station.
German Pat. No. 2,353,774 further describes an apparatus for separating damp veneer sheets. An air blast having adjustable frequency is used to separate the veneer sheet.
Although the above-described prior art apparatuses function satisfactorily for the intended purposes, they are affected by two defects. In the first instance, these apparatuses have limited application. Primarily, they can transport only relative stiff material. Additionally, this prior art device tends to scratch (that is damage) the work pieces. The last defect stems from the fact that there is always relative motion between the work piece and the conveying devices.
U.S. Pat. No. 3,977,672 is an example of the other type of prior art apparatus adapted for handling flexible sheet material, such as paper. The apparatus is adaptable to be positioned between a feed mechanism and a printing machine. The apparatus consists of a vacuum pick-up leg swingably mounted between the feed mechanism and the print press. The vacuum pick-up leg is disposed above a support table. Sheets which are delivered onto the support table are lifted through an arcuate path by the vacuum pick-up leg and delivered to a pair of feed rolls.
U.S. Pat. No. 3,627,308 describes another prior art apparatus suitable to separate and transport paper sheets. The apparatus consists of a plurality of movable riffling fingers disposed relative to one edge of a stack of sheets. The riffling fingers further control the size of a plurality of orifices through which air escapes to fluff the sheets. As the position of the riffling fingers are adjusted from an initial position to a transitional point, a vacuum picker foot, which is disposed above the stack, lifts the topnost sheet from the stack.
United Kingdom Pat. No. 1,429,483 discloses the use of a vacuum picker to pick up a document from a stack and a vacuum belt to transport the document.
United Kingdom Pat. No. 1,446,104 discloses a vacuum document feed wherein an air jet system is used to separate the uppermost sheet from a stack of sheets. A transport assembly consisting of a vacuum pick-up member, feed rollers and conveyor belt transport the sheet from the stack to a utilization point.
The primary problem which is associated with the last mentioned type of prior art devices, is that these devices are susceptible of damaging the documents. The damage stems primarily from the rubbing action (caused by the relative motion between the document and the conveying devices).
In document handling devices, particularly devices used to feed original documents, it is important that there be no scrubbing action between the document and feed mechanism or the document and the stack. Such scrubbing will result in damage to the original documents. Due to the defects associated with the prior art document handling devices, those devices are not suitable to handle original documents.
Although the invention to be described hereinafter finds use with both types of prior art devices, it is of maximum importance in feeding flexible material, including original documents. In this application there is no scrubbing action between the original document and the transport devices. Therefore, the damage to the document is eliminated.